Intra-aortic balloon assemblies are presently employed in the treatment of heart patients to augment the pumping action of a weak heart. Typically, the intra-aortic balloon assembly is inserted into the femoral artery and is inflated during diastole and deflated during systole to decrease left ventricular pressure and hence provide supportive activity for the heart. Immediately after leftventricular ejection, the intra-aortic balloon is inflated to raise diastolic pressures and to increase coronary perfusion, thereby mechanically assisting and augmenting the pumping action of the heart to remove the full burden of pumpingfrom a weakened or damaged heart.
The intra-aortic balloon is conventionally placed in position by making an incision in the patient's artery and suturing a graft to the artery. The balloon is inserted through the graft and is maneuveredto the desired position. The graft is tied snugly about the catheter in an effort to control bleeding.
An adapter is employed in conjunction with the aforesaid graft to permit unimpeded movement of the balloon to the precise location for optimum pumping while at the same time preventing the egress of any body fluids or blood from the slidingconnection made between the adapter and the graft. This technique is taught for example in FIG. 1 of applicant's issued U.S. Pat. No. 4,122,858.
In applications wherein it is desired to monitor blood pressure and in fact to cleanse and oxygenate the patient's blood, it is possible to employ a Y-shaped adapter of the type disclosed in the aforementioned U.S. Pat. No. 4,122,858. The Y-shaped adapter of U.S. Pat. No. 4,122,858 has an elongated preferably straight hollow main portionwith a pair of hollow branch portions branching off at an angle from the straight hollow portion. The hollow interior of the branch portions communicate with the hollow interior of said hollowmain portion. The main portion of the Y-shaped cannula is inserted into the aorta and is connected thereto. The Y-shaped cannula is formed of a flexible material. The balloon and balloon catheter are inserted into one of the branch portions and the common portion of the Y-shaped cannula. The branch portion receiving the balloon catheter is pinched or otherwise squeezed tight about the balloon catheter to prevent the escape of body fluids while the balloon adapter is moved along the catheter in order to be secured in position just inside the free end of the cannula arm portion receiving the balloon catheter. A coupling is connected to the free end of the remaining branch portion of the Y-cannula for connecting heart-lung apparatus to the Y-shaped cannula to provide the patient with oxygenated blood, for example, through a bypass technique.
In the Y-shaped adapter of aforementioned U.S. Pat. No. 4,122,858, theintra-aortic balloon is inserted directly into blood-flow portion of the cannula rather than in the blind end formed by one of the Y branches. The cannula is constructed to have a constant inner diameter since it has been found that it is not possible to push the intra-aortic balloon from a large diameter tube into a smaller diameter tube. It is possible to push an intra-aortic balloon through members either having a constant inner diameter or from one member having a first inner diameter into the next member having a larger inner diameter. In opposition to this, in order to keepblood turbulence to a minimum, in present perfursion cannulas, it is preferred that the catheter have a large diameter at the end adjacent to the heart-lung machine and taper gradually to a smaller diameter at the end inserted in the aorta.